End user changed email account password
If an end user changes the password for their email account or revokes access to your Nylas application, Nylas returns a 401 or 403 error (see Client error responses: 400-499). The email provider might take up to an hour to revoke the end user's refresh token, but Nylas returns an error immediately.
When this happens, the end user must re-authenticate their account with your Nylas application. For more information, see the v3 Re-authenticate grants documentation or the v2 Respond to stopped accounts documentation.